Sodium cyclamate (sweetener code 952) is an artificial sweetener. It is 30–50 times sweeter than sucrose (table sugar), making it the least potent of the commercially used artificial sweeteners. It is often used with other artificial sweeteners, especially saccharin; the mixture of 10 parts cyclamate to 1 part saccharin is common and masks the off-tastes of both sweeteners.[1] It is less expensive than most sweeteners, including sucralose, and is stable under heating.

Cyclamate was discovered in 1937 at the University of Illinois by graduate student Michael Sveda. Sveda was working in the lab on the synthesis of anti-fever medication. He put his cigarette down on the lab bench, and, when he put it back in his mouth, he discovered the sweet taste of cyclamate.[3][4]

The patent for cyclamate was purchased by DuPont but later sold to Abbott Laboratories, which undertook the necessary studies and submitted a New Drug Application in 1950. Abbott intended to use cyclamate to mask the bitterness of certain drugs such as antibiotics and pentobarbital. In the United States in 1958, it was designated GRAS (Generally Recognized as Safe). Cyclamate was marketed in tablet form for use by diabetics as an alternative tabletop sweetener, as well as in a liquid form. As cyclamate is stable to heat, it was and is marketed as suitable for use in cooking and baking.

Controversy developed when, in 1966, a study reported that some intestinal bacteria could desulfonate cyclamate to produce cyclohexylamine, a compound suspected to have some chronic toxicity in animals. Further research resulted in a 1969 study that found the common 10:1 cyclamate:saccharin mixture to increase the incidence of bladdercancer in rats. The released study was showing that eight out of 240 rats fed a mixture of saccharin and cyclamates, at levels of humans ingesting 350 cans of diet soda per day, developed bladder tumors.[5]

Abbott Laboratories claimed that its own studies were unable to reproduce the 1969 study's results, and, in 1973, Abbott petitioned the FDA to lift the ban on cyclamate. This petition was eventually denied in 1980 by FDA Commissioner Jere Goyan.[7] Abbott Labs, together with the Calorie Control Council (a political lobby representing the diet foods industry), filed a second petition in 1982. Although the FDA has stated that a review of all available evidence does not implicate cyclamate as a carcinogen in mice or rats,[8] cyclamate remains banned from food products in the United States. The petition is now held in abeyance, though not actively considered.[9] It is unclear whether this is at the request of Abbott Labs or because the petition is considered to be insufficient by the FDA.

In 1969 an Abbott Laboratories study involving a 10:1 mixture of cyclamate and saccharin indicated that large amounts of cyclamates fed to rats over prolonged periods of time caused bladdercancer in the test rats.[6] Another 1978 study "concluded that neither saccharin nor cyclamate is likely to be carcinogenic in man."[10] Other studies implicated cyclohexylamine in testicular atrophy in mice.[11][12]

A 2003 paper reports the first epidemiological study designed to investigate the possibility of a relationship between cyclamate and cyclohexylamine and male fertility in humans. It states that "the results demonstrate no effect of cyclamate or cyclohexylamine on male fertility at the present levels of cyclamate consumption."[13]

In Taipei, Taiwan, a city health survey in 2010 found nearly 30% of tested dried fruit products failed a health standards test, most having excessive amounts of cyclamate, some at levels 20 times higher than the legal limit.[14]

^Goyan, Jere E.,Commissioner of Food and Drugs. (4 September 1980). "Cyclamate, Commissioner's Decision, 45 FR 61474" (PDF). Office of the Federal Register. pp. 61474–61530. Retrieved February 8, 2015. [...] approval of cyclamate for use as a sweetening agent in food and for technological purposes in food is denied.

^"High-Intensity Sweeteners". U.S. Food and Drug Administration. 19 May 2014. Retrieved 8 February 2015. Are there any high-intensity sweeteners that are currently prohibited by FDA for use in the United States but are used in other countries? Yes. Cyclamates and its salts (such as calcium cyclamate, sodium cyclamate, magnesium cyclamate, and potassium cyclamate) are currently prohibited from use in the United States.